Catheter to assist the performance of a heart

ABSTRACT

In a catheter ( 2 ) to assist the performance of a heart ( 1 ) with at least one pump ( 7 ), the pump is formed as a rotary pump at the distal end of the catheter ( 2 ), the rotor ( 6 ) lying distally on the outer side being coupled via a magneto coupling with a drive wheel ( 21 ), formed as a hydraulically or pneumatically operated paddle wheel, arranged inside the catheter ( 2 ). The driving fluid is supplied to the paddle wheel via a lumen ( 22 ) of the catheter ( 2 ) and is carried off via a further lumen ( 23 ) of the catheter.

The invention relates to a catheter to assist the performance of a heartwith at least one pump.

After a heart failure, for example a cardiac infarction or other reasonsfor the decrease in the performance of a heart, it is of essentialimportance for intensive care medicine to normalise and stabilise thecardiac function again as rapidly as possible. When for example thevolume output of the heart is distinctly reduced as a result of afailure, it is particularly important to reliably and rapidlyre-establish a corresponding peripheral blood flow in order to preventsecondary damage. The use of heart-lung machines basically allows theessential vital functions to be maintained. A specific adaptation to therespective actual requirements generally does not take place with suchdevices, however. Rather, conventional heart-lung machines are deviceswhich, using external pumps, maintain a forced circulation of bloodwithout systematically entering into the respective requirements of theheart which has been weakened or subjected to a failure.

In surgical interventions, particularly in the vein area, it has alreadybeen proposed to carry out retroinfusion, controlled by venous pressure,from or in veins of the body with the suction of fluid and return of thefluid via a pump. Conventional catheters are used here, the lumina ofwhich allow a suction of fluid and via the lumina of which the return ismade possible at a suitable site. Known devices, particularly for theretroinfusion of blood in coronary veins in the area of myocardialprotection during a brief coronary artery closure within a cardiologicalintervention, are generally devised so that a balloon dilatation of anarteriosclerotically constricted coronary artery is carried out. Inthese cases, a compensation which is adapted to the intervention brieflytaking place respectively can be carried out by the return of bloodwhich has been drawn off in veins. For a continuous restitution of thefull function of a heart, however, the criteria are not taken intoaccount which would be relevant for the full function of the heart, andan intensive provision over a particular period of time is therefore notprovided with such devices. At the same time, the provision of the otherorgans must also be maintained.

In the device known from AT 407 960 B for assisting the performance of aheart, fluid is removed from blood vessels via an external pump and isreturned into blood vessels via a return catheter, in which the returnedquantity of fluid is regulated as a function of measurement values, witha heart ventricle catheter being provided to obtain these measurementvalues. The known device comprised a heart ventricle catheter which isequipped in the cardiac chamber with sensors to measure the volume offluid per unit of time, in which these sensors, in the introduced stateof the heart ventricle catheter, lie in the cardiac chamber and thesesensors are connected with an evaluation circuit in which the ratio ofthe diastolic volume to the systolic volume is evaluated per heartbeator per unit of time in particular the discharge rate and/or thedeviation of the volume conveyed per unit of time by the heart from adefined rated value is evaluated, for example the rated value,calculated from physically specific data for the cardiac output. Thesignal which is generated in this way is passed to the pump, via whichfluid is withdrawn from the cardiac chamber and is recirculated as afunction of the generated signal.

The invention now aims to further develop this known device to theeffect that an external pump can be dispensed with and, at the sametime, the desired pressure increase can be brought into effectsystematically at particular locations. In particular, the fluid flowwhich is improved by the pump is to be developed in a way in which themechanical stress of highly sensitive fluids, such as blood for example,can be kept as low as possible and nevertheless the correspondingimprovement to circulation can be ensured at desired locations. To solvethis problem, the initially mentioned device of the catheter accordingto the invention, which can be used within the scope of the devicedescribed above, consists substantially in that the pump is constructedas a rotary pump at the distal end of the catheter, in which the rotorlying distally on the outside is coupled via a magneto coupling with adrive wheel which is arranged inside the catheter and is formed as apaddle wheel which is operated hydraulically or pneumatically and thedriving fluid is supplied to the paddle wheel via a lumen of thecatheter and is carried off via a further lumen of the catheter. Such anaxial pump, which is directly connected with the catheter, can bebrought with the catheter directly into the desired position and, at thesame time, can be used here with further therapeutic additions such as,for example, a retroperfusion through cyclic occlusion of the bloodvessel by means of a balloon. In order to guarantee a completeuncoupling from the driving medium driving the pump and in particular toensure that simple driving means such as, for example, hydraulically orpneumatically operated paddle wheels can be used, a completelyimpervious separation of the rotor from the drive wheel is achieved bythe magneto coupling which is provided according to the invention, whicheliminates axial passages between the drive wheel and the rotor lyingdistally on the outside. The embodiment is hereby devised according tothe invention so that the drive wheel is formed as a hydraulically orpneumatically operated paddle wheel, with the driving fluid beingsupplied to the paddle wheel via a lumen of the catheter and beingcarried off via a further lumen of the catheter, in which preferably thepaddle wheel is constructed with axial or semi-axial blades. Theoperation of such an arrangement can take place in a simple manner bymeans of correspondingly regulated hydraulic or pneumatic reservoirs,with the driving medium being supplied via corresponding regulatingvalves to the drive wheel which is coupled magnetically with the rotor.

The device is designed in a structurally particularly simple manner suchthat the axis of rotation of the rotor is in alignment with thelongitudinal axis of the catheter or is parallel thereto. A developmentof the catheter which has a correspondingly low wear and is impervious,with, at the same time, a secure mounting of the rotor, can be achievedin that the coupling is formed by bar magnets which, in adjacentchambers separated from each other hydraulically by a sealing wall, atthe distal end of the catheter are respectively connected with the rotorand with the drive wheel so as to be locked against relative rotation,in which preferably the connections, locked against relative rotation,of the drive wheel or of the rotor with the respective bar magnets arerespectively mounted in the walls of the chambers facing away from thesealing wall and facing the drive wheel or the rotor respectively.

The rotor itself can follow design principles such as described forexample in WO 01/70300 A1. The rotary pump shown and described there forconveying blood and other highly sensitive fluids is formed as anexternal electromagnetically driven pump which is not directly suitablefor incorporation into a catheter. The known design namely assumes thatcentrifugal flow components and flow components directed against ahousing are present, in which the flow components directed against thehousing serve primarily for the non-contact mounting and stabilising ofthe rotor in the housing. However, with an arrangement of the rotor atthe distal end of a catheter, a closed housing can not be readilyrealised with regard to flow technology, because such housing walls mustin fact lie at a precisely defined distance from the rotor, which,however, is not readily guaranteed at the distal end of a catheter.However, for the desired conveying capacity with the axial pumpaccording to the invention, provision is also made according to theinvention that the rotor has guide surfaces to produce centrifugal flowcomponents.

The driving fluid can be used within the scope of the invention in orderto be able to operate a balloon for retroperfusion. The embodiment ispreferably devised hereby so that the lumina for the driving fluid areguided through an expandable balloon surrounding the catheter in asealing manner, and that the lumina have separately controllable closuremembers via which driving fluid can arrive in the balloon or out of theballoon into the respective lumina, in which preferably the closuremembers are formed as magneto valves. On inflation of the balloon,additional driving medium is required which can be discharged again oncollapsing of the balloon. This is possible extracorporally on the driveside by means of a reservoir.

The embodiment to assist the performance of a heart according to theinvention, in which fluid is conveyed in blood vessels with the use of apump and the conveyed quantity is able to be regulated as a function ofmeasurement values of a heart ventricle catheter, from which the cardiacoutput is determined, proceeds from a development according to AT 407960 B and is characterised substantially in that the pump is formed asan intravasal rotary pump at the periphery or at the distal end of thecatheter, the rotor of which, lying on the outside, is connected via amagneto coupling with the drive which is arranged inside the catheter.

The invention is explained in further detail below by use of anexemplary embodiment which is illustrated diagrammatically in thedrawings, in which

FIG. 1 shows a diagrammatic illustration of the arrangement of the pumpand of the drive,

FIG. 2 shows a diagrammatic illustration of the distal end of a catheterwhich is used according to the invention, and

FIG. 3 shows an enlarged illustration of the part of the catheterbearing the balloon, in section.

In FIG. 1, a heart is designated by 1, into which a heart ventriclecatheter 2 is introduced. The catheter is introduced here for examplevia the femoral artery and the aortic arch 3 into the heart chamber andcarries a series of sensors 4 via which the volume can be determined.The measurement signals are passed to a control arrangement 5. The heartventricle catheter is formed with several lumina, as additionallyillustrated below in further figures of the drawings, with fluid beingsupplied via such lumina to drive a rotor, arranged at the distal end,which forms the pump to assist the blood circulation and is designatedby 6 in FIG. 1. The positioning of this rotor is indicated in FIG. 1 bythe arrow 8. The driving medium for the rotor or the pump is guided in acircular flow by means of a fluid pump 7 which can be regulated in asynchronised manner as a function of the control signals generated inthe control arrangement 5. The distal region in which the pump isarranged is designated diagrammatically by 8, the catheter 2 having atits distal end a tube 9 leading to the suction end 10. A reservoir fordriving fluid is designated by 11, which provides additional drivingmedium for filling the balloon 12 serving for an occlusion of theartery, and which receives again the volume of driving medium occurringon deflation of the balloon.

The volumetric measurement in the cardiac chamber allows differences tobe reliably detected between the diastolic and systolic volume andallows corresponding correction signals to be made available for theoutput of the synchronised fluid pump 7. Furthermore, in the controlcircuit 5, corresponding fixed values can be provided, such as forexample a defined cardiac output, which is referred to on deviation ofthe measured cardiac output to control the pump.

A retroperfusion can take place via a conventional balloon catheterwhich is occluded in a correspondingly synchronised manner, so that thedirected return is in fact guaranteed during the diastole. Hereby thecorresponding measurement values for the heart rate or for the correctmoment of the diastole can be obtained from ECG data.

In FIG. 2, the distal end of a modified catheter 2 is now illustrated.The end side 13 of this catheter has two pocket-shaped chambers 14 and15, in which bar magnets are respectively arranged. The bar magnet 16 isconnected here at the distal end outwards via a shaft 17 with a rotor18, whereas the bar magnet 19 lying on the inside is connected via ashaft 20 with a drive wheel 21. The drive wheel 21 is formed here as apaddle wheel and is acted upon with fluid via a lumen 22, this fluidflowing off again via the lumen 23 of the catheter. The rotation of thepaddle wheel 21 is regulated here accordingly by corresponding controlof the fluid pressure in the lumen 22 serving for the supply of fluid,in which the magnet 19, which is connected so as to be locked againstrelative rotation with the paddle wheel 21, is set into correspondingrotation. At the outer side, which is completely sealed with respect tothe lumina 22 and 23, the magnet 16 is subsequently entrainedaccordingly and drives the rotor 18 via the shaft 17, whereby a flow isformed in the region of the tube 9, as is indicated by the arrows 22,and which assists the natural blood flow in the vessel 26, illustratedby the arrow 25.

In FIG. 3, the partial region of the balloon 12, which is connected in asealing manner to the catheter 2, is illustrated on an enlarged scale.The two lumina leading away from the fluid pump 7 and back to the fluidpump 7 are designated in turn by 22 and 23. In the region of the balloon12, the wall of these lumina is provided with valves which can beactuated magnetically for example. The valves are indicateddiagrammatically by 27 and 28. An opening of the valve 27 leads to thefluid, coming from the fluid pump 7, which is under pressure, which isindicated by the “+” sign, being pumped into the balloon 12, with whichthe overall quantity of the circulating driving fluid would of course bereduced, in so far as the reservoir 11, indicated diagrammatically inFIG. 1, is not provided. By closing the valve 27, the occlusion isclosed off, the collapsing of the balloon 12 being able to be broughtabout by opening the valve 28 and the fluid now being drawn off via thelumen 23, leading back to the pump, which lumen 23 is at a slightlylower pressure which is indicated by the “−” sign. As the overall volumeof the fluid in the circulating system is now to be reduced, a portionof this volume must be pumped back again into the reservoir 11 accordingto FIG. 1.

1. A catheter to assist the performance of a heart, comprising: at leastone pump, wherein the pump is formed as a rotary pump arranged at adistal end of the catheter, a rotor of said pump being arranged distallyat an outer side of said catheter, and being coupled via a magnetocoupling with a drive wheel arranged inside the catheter and formed as ahydraulically or pneumatically operated paddle wheel; a first lumen ofthe catheter supplying driving fluid to the drive wheel; and a secondlumen of the catheter carrying off driving fluid from the drive wheel.2. Catheter according to claim 1, wherein the drive wheel comprisesaxial or semiaxial blades.
 3. Catheter according to claim 1, wherein anaxis of rotation of the rotor is in alignment with a longitudinal axisof the catheter, or is parallel thereto.
 4. Catheter according to claim1, wherein the magneto coupling is formed of bar magnets, said barmagnets being arranged in adjacent chambers, separated from each otherhydraulically by a sealing wall, at the distal end of the catheter, afirst one of said bar magnets is connected with the rotor so as to belocked against relative rotation with respect to the rotor, and a secondone of said bar magnets is connected with the drive wheel so as to belocked against relative rotation with respect to the drive wheel. 5.Catheter according to claim 4, wherein connections between said firstbar magnet and the rotor, and between said second bar magnet and thedrive wheel, are respectively mounted in walls of the chambers facingaway from the sealing wall and facing toward the drive wheel or therotor respectively.
 6. The catheter according to claim 1, wherein therotor comprises guide surfaces to produce centrifugal flow components.7. The catheter according to claim 1, wherein said first lumen andsecond lumen for the driving fluid are guided through an expandableballoon surrounding the catheter in a sealing manner, and said firstlumen and second lumen each carry separately controllable closuremembers via which driving fluid moves into the balloon or moves out ofthe balloon into the respective first lumen and second lumen.
 8. Thecatheter according to claim 7, wherein the closure members are formed asmagneto valves.
 9. A device for assisting the performance of a heart, inwhich fluid is conveyed in blood vessels, comprising: a pump forconveying the fluid in the blood vessels; means for regulating aconveyed quantity of said fluid; and a heart ventricle catheter, fromwhich cardiac output is determined, wherein the conveyed quantity ofsaid fluid is regulated by said regulating means as a function ofmeasurement values of the heart ventricle catheter, the pump is formedas an intravasal rotary pump on a periphery or at a distal end of thecatheter, and a rotor of the pump is arranged on an outer side of thecatheter and is connected via a magneto coupling with a drive which isarranged inside the catheter.
 10. Catheter according to claim 2, whereinan axis of rotation of the rotor is in alignment with a longitudinalaxis of the catheter, or is parallel thereto.
 11. Catheter according toclaim 2, wherein the magneto coupling is formed of bar magnets, said barmagnets being arranged in adjacent chambers, separated from each otherhydraulically by a sealing wall, at the distal end of the catheter, afirst one of said bar magnets is connected with the rotor so as to belocked against relative rotation with respect to the rotor, and a secondone of said bar magnets is connected with the drive wheel so as to belocked against relative rotation with respect to the drive wheel. 12.Catheter according to claim 3, wherein the magneto coupling is formed ofbar magnets, said bar magnets being arranged in adjacent chambers,separated from each other hydraulically by a sealing wall, at the distalend of the catheter, a first one of said bar magnets is connected withthe rotor so as to be locked against relative rotation with respect tothe rotor, and a second one of said bar magnets is connected with thedrive wheel so as to be locked against relative rotation with respect tothe drive wheel.
 13. The catheter according to claim 2, wherein therotor comprises guide surfaces to produce centrifugal flow components.14. The catheter according to claim 3, wherein the rotor comprises guidesurfaces to produce centrifugal flow components.
 15. The catheteraccording to claim 4, wherein the rotor comprises guide surfaces toproduce centrifugal flow components.
 16. The catheter according to claim5, wherein the rotor comprises guide surfaces to produce centrifugalflow components.
 17. The catheter according to claim 2, wherein saidfirst lumen and second lumen for the driving fluid are guided through anexpandable balloon surrounding the catheter in a sealing manner, andsaid first lumen and second lumen each carry separately controllableclosure members via which driving fluid moves into the balloon or movesout of the balloon into the respective first lumen and second lumen. 18.The catheter according to claim 3, wherein said first lumen and secondlumen for the driving fluid are guided through an expandable balloonsurrounding the catheter in a sealing manner, and said first lumen andsecond lumen each carry separately controllable closure members viawhich driving fluid moves into the balloon or moves out of the ballooninto the respective first lumen and second lumen.
 19. The catheteraccording to claim 4, wherein said first lumen and second lumen for thedriving fluid are guided through an expandable balloon surrounding thecatheter in a sealing manner, and said first lumen and second lumen eachcarry separately controllable closure members via which driving fluidmoves into the balloon or moves out of the balloon into the respectivefirst lumen and second lumen.
 20. The catheter according to claim 5,wherein said first lumen and second lumen for the driving fluid areguided through an expandable balloon surrounding the catheter in asealing manner, and said first lumen and second lumen each carryseparately controllable closure members via which driving fluid movesinto the balloon or moves out of the balloon into the respective firstlumen and second lumen.